1. Field of the Invention
The present invention relates to a printing system, a printing method and a printing program which facilitate printing of document data while ensuring the security of document data.
2. Description of the Related Art
In recent years, personal computers (PC) spread widely through the society as a whole, and they are indispensable to the society, such as increased efficiency of office work, exchange of mails between individuals, and electronic commerce technology. With the spreading of PC, many people are now capable of operating PC.
Therefore, because in almost all cases a person who can operate PC exists in the surroundings, even those who cannot operate PC can receive the benefit of PC by requesting the person to be the operator of PC.
However, a security-related problem arises when printing of document data which contains secret data confidential to the company or the like is performed. When the confidential document data is printed, requesting the unrelated person to be an operator of PC is impossible since there is a possibility that the confidential document data may leak to the outside. But it is also difficult for those who cannot operate PC to print document data.
Moreover, conventionally, as a means for suppression of copying data for printing, the ground tint is used. For example, the ground tint is used for a sheet for printing a certificate of the seal impression. In recent years, a copying machine which can superimpose a ground tint over document data having no ground tint and print the document data with the ground tint superimposed has been developed. See Japanese Laid-Open Patent Application No. 2004-252888
However, in order to superimpose the ground tint on the document data and print it with the conventional copying machine, the user must set up the superimposing of the ground tint for every print job, or must set up the superimposing of the ground tint for all the print jobs of printing document data.
When the superimposing of the ground tint is set up for every print job, the user has to judge whether it is document data on which the ground tint should be superimposed. And the user must perform the manual operation, and it is difficult for the user to make an exact judgment in any case.
When the superimposing of the ground tint is set up for all the print jobs, the document data with the ground tint superimposed is always printed on the copy sheet even in a case in which the superimposing of the ground tint is not needed. There is a problem in that the reproduced image on the copy sheet may be concealed by the unnecessary ground tint, and it is hard for the user to see the image of the original document.